Hydraulic control valve unit

ABSTRACT

A hydraulic control valve unit includes an input port hydraulically coupled to a pump, a working port hydraulically coupled to the working load, and a return port connected to a hydraulic tank. The unit includes a control slide movable into different working positions in an axial direction for controlling a hydraulic flow between the hydraulic ports and a slide housing surrounding the control slide. The control slide includes a control segment which is delimited in the axial direction by a control edge, and cooperates with an axial housing segment of the slide housing for controlling a flow cross section for hydraulic flow at the control segment. The control slide is rotationally driven about an axis of rotation in a rotational direction. The control edge of the control segment or the housing segment cooperating with the control segment is designed such that the flow cross section has a different size depending on a rotational position of the control slide.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/291,133, filed Mar. 4, 2019, which claims priority to German PatentApplication Ser. No. 102018203436.2, filed Mar. 7, 2018, the disclosuresof which are hereby incorporated by reference in their entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates to a hydraulic control valve unit foractuating a hydraulic operating load.

BACKGROUND

A control valve unit has an axially displaceable control slide forcontrolling a hydraulic flow, e.g., from a hydraulic pump connected tothe control valve unit to the likewise connected hydraulic operatingload. Different axial operating positions of the control slide are usedto regulate or control the hydraulic flow between the pump, theoperating load and a hydraulic tank with respect to direction andquantity.

There is a need, however, for improving the hydraulic functionality ofthe control valve unit.

SUMMARY

In one embodiment of the present disclosure, a hydraulic control valveunit has a plurality of hydraulic ports for actuating a hydraulicoperating load. These hydraulic ports include at least one input portfor hydraulic connection to a hydraulic pump, which pumps hydraulicfluid (oil for example) through the control valve unit to the operatingload. The hydraulic ports further include at least one working port forhydraulic connection to the hydraulic connector of the operating load,and at least one return port that can be connected to an externalhydraulic tank or sump. To control the hydraulic flow between thehydraulic ports, the control valve unit has a control slide that can betransferred in the axial direction into different working positions. Forexample, the system pressure can be brought to the working ports in thisway. The control slide cooperates with a slide housing that surroundsthe control slide. Individual ports can be hydraulically connected toone another by means of the slide housing depending on the respectiveworking position of the control slide.

The control slide has at least one control segment, which is delimitedin the axial direction by a control edge and interacts with an axialhousing segment of the slide housing to control a flow cross section forhydraulic flow at this control segment. In addition to its axialdisplaceability, the control slide can also be driven rotationally in arotational direction about an axis of rotation that runs parallel to theaxial direction. The control edge of at least one control segment, orthe housing segment cooperating with this control segment, is designedsuch that the flow cross section for hydraulic flow at this controlsegment has different sizes depending on the different rotationalpositions of the control slide.

A single axial working position of the control slide can consequentlyinclude several different rotational working positions of the controlslide at a control segment, with correspondingly different hydraulic andtechnical effects.

In other words, different rotational positions of a geometricallyappropriately shaped control edge or a geometrically appropriatelyshaped housing segment enable different flow cross sections for thehydraulic flow at this control segment.

In this way, the functionalities of the control valve unit (e.g.,adjusting hydraulic-physical variables, hydraulic response behavior,control of the volume flow or the flowing hydraulic quantity, number ofdifferent hydraulic operating positions/states) can be expanded. Thecontrol slide that is used ensures that this functional expansion inrelation to conventional control valve units can be created with lowtechnical effort and thus cost-effectively.

In summary, flow cross sections for hydraulic flow between the hydraulicports during working operation of the control valve unit can be adjusteddifferently, by providing a suitable geometric dimensioning of thecontrol edge of at least one control segment or a suitable geometricdimensioning of the axial housing segment of the slide housing thatinteracts with this control segment.

To adjust different functionalities of the control valve unit, definedangles of rotation by which the control unit can be driven by means of asuitable drive unit are provided. Depending on the respective technicalapplication of the control valve unit, it is possible to vary the axialdisplacement paths, the flow cross sections and the angles of rotationof the control slide, in order to implement the desired functionalitiesof the control valve unit.

The control slide can have multiple control segments arranged in theaxial direction. On at least one of these control segments, the flowcross section for hydraulic flow is differently sized depending ondifferent rotational positions of the control slide. In this way, asuitable control slide can be provided for different control valve unitswith different functionalities.

In particular, the control slide has at least two control segments, ofwhich at least one control segment enables a constant flow cross sectionfor hydraulic flow at different rotational positions of the controlslide. A control slide of this kind creates the prerequisite for beingable to provide, with an unchanged flow cross section in at least onecontrol segment, different-sized flow cross sections on at least oneadditional control segment of the control slide. The variationpossibilities with respect to the hydraulic functionality of the controlvalve unit are further increased in this way.

In particular, an unchanged flow cross section in one control segmentwith different flow cross sections in at least one additional controlsegment due to rotational movements of the control slide can beimplemented by a control edge of the control segment that has a regularprofile, e.g., a regular zigzag line, partially or entirely along thecircumferential direction or the rotational direction.

The concept of different flow cross sections for hydraulic flow at onecontrol segment for different rotational positions of the control slidecan be applied to functionally different control segments within acontrol valve unit.

One control segment is a regulating control segment that is arranged inan outflow region of the slide housing. This outflow region connects theinput port or a connecting duct directly adjoining it to the slidehousing. The regulating control segment can control the hydraulic flowcoming from the input port. Depending on the desired functionality, aconstant or a different-sized flow cross section for hydraulic flow canbe realized with rotational movements of the control slide at theregulating control segment. For example, a constant flow cross sectionis present at the regulating control segment for one rotating controlslide, whereas the flow cross section has differing sizes in at leastone further control segment. Thus, different functionalities can beachieved for constant hydraulic conditions on the regulating controlsegment, e.g., a continuously variable increase of the flow crosssection or throttling in the region of additional control segments.

For example, turning or rotating the control slide in an axial workingposition can have the effect that, with an unchanged flow cross sectionat the regulating control segment, the flow cross section at a so-calledoutlet control segment arranged between the working port and the returnport can be increased in order to reduce a hydraulic back-pressure inthe direction of the return port and the hydraulic tank. Conversely, theflow cross section at the outlet control segment can be reduced in atargeted manner with an appropriate rotation of the control slide, inorder to achieve throttling in the direction of the hydraulic tank. Thisbrings about an increased back-pressure, which can reduce or avoidflow-induced cavitation effects and consequent stresses on seals andother components of the control valve unit.

Different functions or states of the control valve unit can also beachieved if the flow cross section at the regulating control segment isequal to zero and thus remains closed, i.e., if hydraulic fluid comingfrom the input port cannot continue to flow at the regulating controlsegment. By rotation of the control slide at the already mentionedoutlet control segment, for example, the flow cross section can beopened so that the working port and the return port are hydraulicallyconnected to one another. This principle can also be extended to asecond working port and a second return port by means of an additionaloutlet control segment. In this manner, so-called floating positions ofthe control valve unit can be achieved directly, solely by rotation ofthe control slide, without first having to move the control slide pastdifferent functional positions or axial working positions by axialdisplacement before it reaches the floating position.

In another embodiment of the regulating control segment, the flow crosssection at the regulating control segment can be of different sizes inone axial working position by turning or rotating the control slide.Thereby, the control valve unit achieves a larger flow opening in theoutflow area of the slide housing, lower pressure losses andconsequently a higher efficiency. In this variant, the flow crosssection is constant in at least one additionally present control segment(e.g., the above-mentioned outlet control segment) so that no specificgeometry of the control edge or the housing segment for different flowcross sections is necessary there when rotating the control slide.

The above explanations of the regulating control segment with either aconstant or a different flow cross section for a rotating control slideand a combination with additional control segments can be appliedaccordingly to other control segments of the control slide. For example,this can be a so-called inlet control segment, which is arrangedhydraulically upstream from the working port and can control thehydraulic flow to the working port. In another application, the controlsegment is a so-called outlet control segment, which is arrangedhydraulically between the working port and the return port and cancontrol the hydraulic flow to the return port.

In particular, the control slide has two outlet control segments, eachof which is associated with one of two available working ports. In thisway, the hydraulic connection between each working port and theassociated return port can be controlled. Depending on the desired modeof operation of the control valve unit, the two outlet control segmentsand their outlet control edges can be geometrically dimensioneddifferently or identically.

In another embodiment, the control slide has two outlet control segmentswhich are arranged mirror-symmetrically relative to one another withrespect to a plane of symmetry arranged perpendicular to the axialdirection. This supports technically simple production of the controlslide and a uniform mode of operation of the control valve unit betweenthe working ports and the return ports.

To implement different flow cross sections at a control segment or atthe housing segment cooperating therewith, the control edge of thiscontrol segment may be provided with a non-uniform or asymmetricgeometric profile in the circumferential direction or the rotationaldirection (i.e., along the geometrical development) which, in contrastto a symmetrical control edge, would bring about an equal-sized flowcross section at this control segment during rotation of the controlslide, independently of the angle of rotation.

The geometrical profile of the control edge is such that the edge has atleast one axially outer edge portion and at least one axially inner edgeportion. The axially inner edge portion is offset axially inwardrelative to the axially outer edge portion, whereby the control segmenthas a lesser axial extent in the region of the inner edge portion thanin the region of the outer edge portion. This axially offset arrangementof edge portions of the control edge can be implemented by variousgeometries, for example, by straight-line portions or by wave-shaped,more particularly sinusoidal line portions.

The desired non-uniform geometrical progression of the control edgealong the rotational direction is easily supported in terms of design inthat the axially inner edge portion, or all axially inner edge portions,extends or extend along the rotational direction by less than 180° asviewed in a 360° developed view of the outlet control segment.

In a further embodiment, the axially inner edge portion runs partiallyor completely along the rotational direction parallel to the rotationaldirection. This supports an easily produced manufacture of the controlsegment for differently sized flow cross sections.

Further, the axially inner edge portion runs along the rotationaldirection, at least in part, at an angle greater than 0° and less than90° relative to the rotational direction. In this way, the flow crosssection can be adjusted continuously and therefore even more variably.This can be used, for example, to modify the flow cross section at acontrol segment within the same operating position of the control valveunit as needed, if the hydraulic flow or the volume flow is to beinfluenced.

Different flow cross sections at a control segment, or at the housingsegment cooperating therewith, can be achieved by different rotationalpositions of the control slide if the geometric structure of thecooperating axial housing segment is designed correctly. This can beaccomplished independently of or in combination with a specific controledge geometry. An adaptation of this kind is that the housing segmentcooperating with a control segment, more particularly in the region ofthe already mentioned axially inner edge portion of the control edge,has a greater axial extent than the largest axial extent of the controlsegment.

Functionalities of the control valve unit are controlled in particularby at least one of an operating lever for a user, an electronic controlunit, signals of an electronic bus (e.g., a CAN bus) or a stepper motor.

The stepper motor may convert electronic input signals into proportionaloutput signals or mechanical movements. In this case, the stepper motoris coupled in a suitable manner (e.g., by means of a toothed rack) tothe control slide, in order to transfer the control slide into differentaxial working positions. The same stepper motor, or alternatively anadditional suitable drive unit (e.g., stepper motor, spindle drive),rotationally drives the control slide in the rotational direction.Different functionalities of the control valve unit are each associatedwith defined rotational angles of the control slide, which are effectedby the drive unit.

The control valve unit is installed in an agricultural vehicle, moreparticularly a tractor, and acts there as a hydraulic control device.Different hydraulic loads (e.g., hydraulic motor, front loader,three-point hitch, manure spreader, additional attached implements) onthe agricultural vehicle can be actuated in this way. For example,increases of efficiency due to reduced residual pressures can beachieved on such loads. For certain loads (e.g., front loader), possiblecavitation can be avoided in a technically simple manner.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned aspects of the present disclosure and the manner ofobtaining them will become more apparent and the disclosure itself willbe better understood by reference to the following description of theembodiments of the disclosure, taken in conjunction with theaccompanying drawings, wherein:

FIG. 1 shows a plan view of a partially represented control valve unitwith a view of essential components within a control valve housing ofthe control valve unit,

FIG. 2 shows a perspective partial representation of a first embodimentof the control slide used in the control valve unit,

FIG. 3a shows an enlarged developed view of a regulating control segmentaccording to detail III-A in FIG. 1,

FIG. 3b shows an enlarged developed view of a regulating control segmentaccording to detail III-B in FIG. 1,

FIG. 3c shows an enlarged developed view of a regulating control segmentaccording to detail III-C in FIG. 1,

FIG. 4 shows three axial portions of a slide housing, each as adeveloped view of a housing segment that cooperates with the respectiveassociated control segment according to FIG. 3a or FIG. 3b or FIG. 3 c,

FIG. 5 shows the developed views according to FIG. 3a , FIG. 3b , FIG.3c and FIG. 4 in a first working position of the control slide,

FIG. 6 shows the developed views according to FIG. 3a , FIG. 3b , FIG.3c and FIG. 4 in an additional working position of the control slide,

FIG. 7 shows the developed views according to FIG. 3a , FIG. 3b , FIG.3c and FIG. 4 in an additional working position of the control slide,

FIG. 8 shows the developed views according to FIG. 3a , FIG. 3b , FIG.3c and FIG. 4 in an additional working position of the control slide,

FIG. 9 shows the developed views according to FIG. 3a , FIG. 3b , FIG.3c and FIG. 4 of the first working position of the control slideaccording to FIG. 5, but in an additional embodiment of the slidehousing,

FIG. 10 shows the developed views according to FIG. 9 in an additionalworking position of the control slide,

FIG. 11 shows the developed view of the first outlet control segment inan additional embodiment, and

FIG. 12 shows the developed view of the first outlet control segment inan additional embodiment.

Corresponding reference numerals are used to indicate correspondingparts throughout the several views.

DETAILED DESCRIPTION

The embodiments of the present disclosure described below are notintended to be exhaustive or to limit the disclosure to the preciseforms disclosed in the following detailed description. Rather, theembodiments are chosen and described so that others skilled in the artmay appreciate and understand the principles and practices of thepresent disclosure.

FIG. 1 shows a control valve unit 10 with a merely schematicallyrepresented drive unit 12 for driving a control slide 14. Outside thedrive unit 12, a control valve housing 16 of the control valve unit 10is opened and reveals a view of components of the control valve unit 10.

The drive unit 12 may include at least one stepper motor for driving thecontrol slide 14. Depending on its actuation, the control slide 14 canbe moved translationally in an axial direction 18 and rotatably in therotational direction 20 about an axis of rotation 36 running parallel tothe axial direction. Two working ports 22, 24 for hydraulic connectionof a hydraulic working load not shown here (e.g., a double actingcylinder) are arranged on the control valve housing 16. The firstworking port 22 corresponds to the function “extend cylinder” withrespect to the working load, while the second working port 24corresponds to the function “retract cylinder” with respect to theworking load. Depending on the defined working positions of the controlslide 14, the two return ports 26, 28 can be hydraulically connected tothe working ports 22, 24. Both hydraulic ports 26, 28 are connected toan external hydraulic tank or sump (not shown) for hydraulic fluid(e.g., oil).

An input port 30 is connected to a hydraulic pump (not shown) thatdelivers hydraulic fluid from the hydraulic tank to the control valveunit 10. The input port 30 is connected hydraulically by a connectionduct 32 to an outflow region 38 of the slide housing 34. The slidehousing 34 surrounds the control slide 14 in the circumferentialdirection thereof, i.e., in the rotational direction 20, by a radialdistance. The radial distance varies in the axial direction 18 between aminimum in order to guarantee axial movability of the control slide 14relative to the slide housing 34, and larger radial distances, whichenable flow of hydraulic fluid through the slide housing 34. Thus, theinput port 30, the working ports 22, 24 and the return ports 26, 28 canbe hydraulically connected to one another depending on the desiredfunctionality of the control valve unit 10 and the respective axial orrotational working position of the control slide 14.

The drive unit 12 or the stepper motor thereof is drivingly connected tothe control slide 14, (e.g., via a toothed rack). The drive unit 12converts electronic input signals into mechanical movements of thecontrol slide 14. These mechanical movements are linear or axialmovements in the axial direction 18 and rotational movements about theaxis of rotation 36 along the rotational direction 20. The drive unit 12uses either the same stepper motor for the axial and rotationalmovements of the control slide 14, or the stepper motor generates theaxial movements, while an additional drive unit (e.g., a second steppermotor, spindle drive, etc.) generates the rotational movements.

With respect to the functionalities of the control valve unit 10, thedrive unit 12 moves the control slide 14 into different operatingpositions such as neutral position, extension position (extendcylinder), retracted position (retract cylinder), floating position andoptionally additional adjustable intermediate positions. In this way,the hydraulic flow can be controlled and regulated with respect to flowdirection and flow quantity between the input port 30, the working ports22, 24 and the return ports 26, 28.

In the “extension position” operating state, the control slide 14 hasbeen moved axially to the left with respect to the position in FIG. 1.In this way, hydraulic fluid can flow from the input port 30 via theoutflow region 38 between the control slide 14 and the slide housing 34to the first working port 22. Hydraulic fluid from the second workingport 24 can flow between the control slide 14 and the slide housing 34,as well as via the associated return port 28 to the hydraulic tank.

In the “retraction position” operating state, the control slide 14 hasbeen moved axially to the right relative to the position in FIG. 1. Inthis position of the control slide 14, hydraulic fluid can flow from theinput port 30 via the outflow region 38, between the control slide 14and the slide housing 34 to the second working port 24. Hydraulic fluidfrom the first working port 22 can flow between the control slide 14 andthe slide housing 34, as well as via the associated return port 26 tothe hydraulic tank.

FIG. 2 illustrates the control slide 14 in a cut-out with an outletcontrol segment 58 and with an inlet control segment 42. Along the axialdirection 18, the control slide 14 according to FIG. 1 has a regulatingcontrol segment 56, the outlet control segment 58, the inlet controlsegment 42, and an additional outlet control segment 60.

The control segments 56, 58, 60 are shown in FIGS. 3a, 3b and 3c as 360°developed views along the rotational direction 20, or thecircumferential direction of the control slide 14. The individualcontrol segments 56, 58, 60 are respectively arranged in the regions ofdetails III-A, III-B, III-C in FIG. 1. The outlet control segment 58 isarranged in the hydraulic connection between the second working port 24and the associated return port 28, while the outlet control segment 60is arranged in the hydraulic connection between the first working port22 and the associated return port 26.

The two outlet control segments 58, 60 in the embodiment according toFIGS. 3b and 3c , and in FIGS. 5-10, are arranged mirror-symmetricallyrelative to one another with respect to a plane of symmetry runningperpendicular to the axial direction 18. In additional embodiments, thetwo outlet control segments 58, 60 can be arranged asymmetricallyrelative to one another and constructed differently, depending on thetechnical application and the dimensioning of the control valve unit 10.

The slide housing 34 has a regulating housing segment 62, an inlethousing segment 44, and two outlet housing segments 64, 66. Thehydraulic flow (in particular, the flow quantity of the hydraulic fluid,the volume flow, etc.) at the housing segments 44, 62, 64, 66 can becontrolled on the basis of axial or rotational changes of position ofthe control slide 14.

The control segments 42, 56, 58, 60 each cooperate with one of thehousing segments 44, 62, 64, 66 in order to control the flow crosssection for hydraulic fluid at the respective housing segment 44, 62,64, 66, i.e., to enlarge or reduce it, wherein the reduction can go tozero. The control segments 42, 56, 58, 60 are each delimited in theaxial direction 18 by at least one control edge 46, 68, 70, 76. Thespecific profile thereof can determine the flow cross section, dependingon the geometric design along the rotational direction 20.

The regulating control segment 56 according to FIG. 3a has a regulatingcontrol edge 68 with a substantially zigzag profile along the rotationaldirection 20. The outlet control segment 58 according to FIG. 3b has anoutlet control edge 70. The latter has two axially outer edge portions72 along the rotational direction 20, and an axially inner edge portion74 offset axially inward therefrom. The outlet control segment 60 has anoutlet control edge 76 which, due to the mirror-symmetric structure ofthe outlet control segment 60 relative to the outlet control segment 58,likewise contains the two axially outer edge portions 74 and the axiallyinner edge portion 72. The axially inner edge portion 72 extends alongthe rotational direction 20 by less than 180° relative to the 360°developed view of the entire outlet control segment 58 or 60 along therotational direction 20. The axially inner edge portion 72 also runsparallel to the rotational direction 20.

The housing segments 44, 62, 64, 66 shown in FIG. 1 are represented inFIG. 4 (analogously to the control segments 56, 58, 60 in FIGS. 3a, 3band 3c ) as 360° developed views of the housing segments 62, 64, 66along the rotational direction 20.

The regulating control segment 56 is arranged in the outflow region 38of the slide housing 34. Depending on an adjusted working position ofthe control slide 14 and thus an axial relative position of theregulating control segment 56 relative to the regulating control segment62, the regulating control edge 68 influences whether and how muchhydraulic fluid flows from the input port 30 through the regulatingcontrol segment 62.

The outlet control segment 58 is associated with the second working port24 and the return port 28, while the outlet control segment 60 isassociated with the first working port 22 and the return port 26.Depending on the respective axial or rotational relative positions ofthe outlet control segments 58 and 60 relative to the outlet controlsegment 64 or 66, respectively, the outlet control edge 70 or 76respectively influences whether and how much hydraulic fluid flowsthrough the respective automatic control segment 64 or 66 to therespective working port 24 or 22 or to the respective return port 28 or26.

The positions of the regulating control segment 56 and the outletcontrol segments 58, 60 in FIG. 5 are such that no hydraulic fluid flowsthrough the respective housing segment 62, 64, 66. The flow crosssection for the hydraulic flow at the housing segment 62, 64, 66 istherefore equal to zero. In particular, this working position of thecontrol slide 14 corresponds to a “neutral position” operating state ofthe control valve unit 10.

Proceeding from FIG. 5, the control slide 14 in FIG. 6 has been shiftedaxially to the left. No rotational movement of the control slide 14 hasbeen carried out. Therefore, a flow cross section 78 greater than zeroarises at the regulating housing segment 62. The total surface area ofthe regulating flow cross section 78 corresponds to the sum of the fivecross-hatched triangular areas. The axial displacement of the controlslide 14 according to FIG. 6 results in an outlet flow cross section 80at the outlet housing segment 64 that is greater than zero, thecross-sectional area of which results from the two hatched rectangularareas. The working position of the control slide 14 according to FIG. 6,for example, brings about a hydraulic flow from the input port 30 to thefirst working port 22 and a hydraulic flow from the second working port24 to the return port 28.

Proceeding from FIG. 5, the control slide 14 in FIG. 7 has been shiftedaxially to the left and rotated by 180° along the rotational direction20. In FIG. 7, this results in an outlet flow cross section 80-1, shownas a hatched area in FIG. 7, at the outlet segment 64 that is largerthan the flow cross section in FIG. 6. The size of the regulating flowcross section 78 remains unchanged due to the uniform symmetricalprofile of the regulating control edge 68 in the rotational direction20. In this way, the hydraulic flow cross section between the secondworking port 24 and the return port 28 can be increased if necessary,with unchanged hydraulic conditions at the regulating control segment62. Consequently, the flow resistance and the back pressure within thishydraulic connection are reduced.

Proceeding from FIG. 5, the control slide 14 in FIG. 8 has been rotatedby 180° along the rotational direction 20. The hydraulic flow at theregulating housing segment 62 therefore remains blocked or interrupted.Due to the rotational movement of the control slide 14, however,respective flow cross sections 80-2 and 82-2 have been achieved at therespective outlet housing segments 64 and 66. The first working port 22and the return port 26 are connected hydraulically to one another, andthe second working port 24 and the return port 28 are connectedhydraulically to one another. The two working ports 22, 24 are thusconnected hydraulically to one another via the hydraulic tank connectedto the return ports 26, 28. The working position of the control slide 14according to FIG. 8, for example, can thus achieve a floating positionas the operating position of the control valve unit 10 with a singlerotational movement. Consequently, conventionally necessaryspace-intensive axial position changes of the control slide 14 whilecrossing other operating positions are avoided when a functionalityaccording to FIG. 8 (e.g., floating position) is to be adjusted for thecontrol valve unit 10.

In comparison to the slide housing 34 according to FIG. 5, the outlethousing segments 64, 66 in the embodiment according to FIG. 9 havelonger dimensions in the axial direction 18. The outlet housing segments64, 66 in this case are each axially lengthened by a housing protrusion84 in the region of the axially inner edge portion 72. The outlethousing segments 64, 66 thus have a larger axial extent in the region ofthe axially inner edge portion 72 than the largest axial extent of theoutlet control segments 58, 60.

Proceeding from the working position according to FIG. 9, the controlslide 14 can be transported axially to the left in order to achieve thesame regulating flow cross section 78 (FIG. 10) as in FIG. 6. Due to thehousing protrusion 84, however, the outlet flow cross section 80-3 atthe outlet housing segment 64 according to FIG. 10 is smaller than theoutlet flow cross section 80 at the outlet housing segment 64 accordingto FIG. 6. With the reduced outlet flow cross section 80-3, a throttlingof the hydraulic flow in the region of the return port 28 and in thedirection of the hydraulic tank connected thereto can be achieved. Thiscauses an increased back pressure and avoids possible cavitation effectsin the hydraulic conduction paths within the control valve unit 10.

FIG. 11 shows another embodiment of the outlet control segment 58. Inthis embodiment, the axially inner edge portion 72 of the outlet controledge 70 has two sub-portions 72-1, 72-2 succeeding one another in therotational direction 20. The sub-portion 72-1 runs as a straight line atan angle of greater than 0° and less than 90° (approximately 35° in FIG.11) relative to the rotational direction 20. The shorter sub-portion72-2 runs parallel to the rotational direction 20.

FIG. 12 shows another embodiment of the outlet control segment 58. Inthis embodiment, the axially inner edge portion 72 and the axially outeredge portion 74, in contrast to the variant shown in FIG. 3b , each havetwo circular arc-shaped sub-portions 72-3 and 74-3.

The features disclosed with reference to the outlet control segment 58can also or alternatively be implemented, singly or in combination, onlyon outlet control segment 60. In addition, features illustrated on thebasis of a control segment 42, 56, 58, 60 or of a housing segment 44,62, 64, 66 can be implemented singly or in combination in additionalembodiments, alternatively or additionally on a different disclosedcontrol segment or disclosed housing segment.

The illustrated embodiment of the control valve unit 10 is merely forthe sake of example. Individual features can be modified in additionalembodiments of the control valve unit. For example, functionally ornumerically different hydraulic ports can be implemented. Thedefinition, number and arrangement of control segments and housingsegments cooperating therewith can also be different in furtherembodiments of the control valve unit.

While exemplary embodiments incorporating the principles of the presentdisclosure have been disclosed hereinabove, the present disclosure isnot limited to the disclosed embodiments. Instead, this application isintended to cover any variations, uses, or adaptations of the disclosureusing its general principles. Further, this application is intended tocover such departures from the present disclosure as come within knownor customary practice in the art to which this disclosure pertains andwhich fall within the limits of the appended claims.

The invention claimed is:
 1. A hydraulic control valve unit configuredto actuate a hydraulic working load, comprising: a plurality ofhydraulic ports comprising an input port configured to be hydraulicallycoupled to a pump, a working port configured to be hydraulically coupledto the working load, and a return port configured to be connected to ahydraulic tank; a control slide movable into different working positionsin an axial direction and in a rotational direction about an axis ofrotation; and a slide housing with an inner diameter that surrounds thecontrol slide such that the control slide is movable in the axialdirection and in the rotational direction within the inner diameter ofthe slide housing to control hydraulic flow between the plurality ofhydraulic ports; wherein the control slide comprises a first controlsegment which is delimited in the axial direction by a first controledge; wherein the slide housing comprises a first housing segment thatcooperates with the first control segment to control a first flow crosssection for hydraulic flow within the inner diameter of the slidehousing at the first control segment; wherein the first control edge ofthe first control segment in cooperation with the first housing segmentis configured to modify size of the first flow cross section at thefirst control segment based on rotational position of the control slidewithin the slide housing; wherein when the control slide is in a firstaxial position and a first rotational position within the slide housing,the first control edge of the first control segment in cooperation withthe first housing segment is configured to create a disjoint flow crosssection at the first control segment within the inner diameter of theslide housing, where the disjoint flow cross section includes separatefirst and second flow cross section areas; and wherein when the controlslide is in the first axial position and a second rotational positionwithin the slide housing, where the second rotational position isdifferent from the first rotational position, the first control edge ofthe first control segment in cooperation with the first housing segmentis configured to create a unitary flow cross section at the firstcontrol segment within the inner diameter of the slide housing, wherethe unitary flow cross section includes a single flow cross sectionarea; wherein the disjoint flow cross section and the unitary flow crosssection have different sizes.
 2. The control valve unit according toclaim 1, wherein the single flow cross section area of the unitary flowcross section is larger than the combined first and second flow crosssection areas of the disjoint flow cross section.
 3. The control valveunit according to claim 2, wherein the first control edge of the firstcontrol segment comprises an axially inner edge portion and an axiallyouter edge portion, where the axially inner edge portion is offsetinwardly in the axial direction relative to the axially outer edgeportion; wherein when the control slide is in the first axial positionand the first rotational position within the slide housing, the firstflow cross section area of the disjoint flow cross section is betweenthe axially inner edge portion of the first control edge and the firsthousing segment, and the second flow cross section area of the disjointflow cross section is between the axially outer edge portion of thefirst control edge and the first housing segment; and wherein when thecontrol slide is in the first axial position and the second rotationalposition within the slide housing, the single flow cross section area ofthe unitary flow cross section is between the axially inner edge portionof the first control edge and the first housing segment.
 4. The controlvalve unit according to claim 3, wherein the axially outer edge portionand the axially inner edge portion extend along the rotationaldirection.
 5. The control valve unit according to claim 3, wherein theaxially outer edge portion extends along a portion of the axis ofrotation.
 6. The control valve unit according to claim 3, wherein theaxially inner edge portion extends along the rotational direction at anangle greater than 0° and less than 90° along the rotational direction.7. The control valve unit according to claim 1, wherein the firstcontrol segment of the control slide comprises an inlet control segmenthydraulically upstream of the working port to control hydraulic flow tothe working port.
 8. The control valve unit according to claim 1,wherein the first control segment of the control slide comprises anoutlet control segment hydraulically positioned between the working portand the return port to control hydraulic flow to the return port.
 9. Thecontrol valve unit according to claim 1, wherein the control slidefurther comprises a second control segment which is delimited in theaxial direction by a second control edge: wherein the slide housingcomprises a second housing segment that cooperates with the secondcontrol segment to control a second flow cross section for hydraulicflow within the inner diameter of the slide housing at the secondcontrol segment; wherein the second control edge of the second controlsegment in cooperation with the second housing segment is configuredsuch that for a fixed axial position of the control slide within theslide housing, the second flow cross section at the second controlsegment is constant in size for any rotational position of the controlslide within the slide housing.
 10. The control valve unit according toclaim 9, wherein the second control segment of the control slidecomprises a regulating control segment in an outflow region of the slidehousing which connects the slide housing to the input port.
 11. Ahydraulic control valve unit configured to actuate a hydraulic workingload, comprising: a plurality of hydraulic ports comprising an inputport configured to be hydraulically coupled to a pump, a working portconfigured to be hydraulically coupled to the working load, and a returnport configured to be connected to a hydraulic tank; a control slidemovable into different working positions in an axial direction and in arotational direction about an axis of rotation; and a slide housing withan inner diameter that surrounds the control slide such that the controlslide is movable in the axial direction and in the rotational directionwithin the inner diameter of the slide housing to control hydraulic flowbetween the plurality of hydraulic ports; wherein the control slidecomprises a first control segment which is delimited in the axialdirection by a first control edge, where the first control edgecomprises an axially inner edge portion and an axially outer edgeportion where the axially inner edge portion is offset inwardly in theaxial direction relative to the axially outer edge portion; wherein theslide housing comprises a first housing segment that cooperates with thefirst control segment to control a first flow cross section forhydraulic flow within the inner diameter of the slide housing at thefirst control segment; wherein the first control edge of the firstcontrol segment in cooperation with the first housing segment isconfigured to modify size of the first flow cross section at the firstcontrol segment based on rotational position of the control slide withinthe slide housing; wherein when the control slide is in a first axialposition and a first rotational position within the slide housing, thefirst control edge of the first control segment in cooperation with thefirst housing segment is configured to create a disjoint flow crosssection at the first control segment within the inner diameter of theslide housing, where the disjoint flow cross section includes separatefirst and second flow cross section areas; and wherein when the controlslide is in the first axial position and a second rotational positionwithin the slide housing, where the second rotational position isdifferent from the first rotational position, the first control edge ofthe first control segment in cooperation with the first housing segmentis configured to create a unitary flow cross section at the firstcontrol segment within the inner diameter of the slide housing, wherethe unitary flow cross section includes a single flow cross sectionarea; wherein the disjoint flow cross section and the unitary flow crosssection have different sizes.
 12. The control valve unit according toclaim 11, wherein the single flow cross section area of the unitary flowcross section is larger than the combined first and second flow crosssection areas of the disjoint flow cross section.
 13. The control valveunit according to claim 11, wherein when the control slide is in thefirst axial position and the first rotational position within the slidehousing, the first flow cross section area of the disjoint flow crosssection is between the axially inner edge portion of the first controledge and the first housing segment, and the second flow cross sectionarea of the disjoint flow cross section is between the axially outeredge portion of the first control edge and the first housing segment;and wherein when the control slide is in the first axial position andthe second rotational position within the slide housing, the single flowcross section area of the unitary flow cross section is between theaxially inner edge portion of the first control edge and the firsthousing segment.
 14. The control valve unit according to claim 13,wherein the axially outer edge portion and the axially inner edgeportion extend along the rotational direction.
 15. The control valveunit according to claim 13, wherein the axially outer edge portionextends along a portion of the axis of rotation.
 16. The control valveunit according to claim 13, wherein the axially inner edge portionextends along the rotational direction at an angle greater than 0° andless than 90° along the rotational direction.
 17. The control valve unitaccording to claim 13, wherein the control slide further comprises asecond control segment which is delimited in the axial direction by asecond control edge: wherein the slide housing comprises a secondhousing segment that cooperates with the second control segment tocontrol a second flow cross section for hydraulic flow within the innerdiameter of the slide housing at the second control segment; wherein thesecond control edge of the second control segment in cooperation withthe second housing segment is configured such that for a fixed axialposition of the control slide within the slide housing, the second flowcross section at the second control segment is constant in size for anyrotational position of the control slide within the slide housing. 18.The control valve unit according to claim 17, wherein the second controlsegment of the control slide comprises a regulating control segment inan outflow region of the slide housing which connects the slide housingto the input port.
 19. A hydraulic control valve unit configured toactuate a hydraulic working load, comprising: a plurality of hydraulicports comprising an input port configured to be hydraulically coupled toa pump, a working port configured to be hydraulically coupled to theworking load, and a return port configured to be connected to ahydraulic tank; a control slide movable into different working positionsin an axial direction and in a rotational direction about an axis ofrotation; and a slide housing with an inner diameter that surrounds thecontrol slide such that the control slide is movable in the axialdirection and in the rotational direction within the inner diameter ofthe slide housing to control hydraulic flow between the plurality ofhydraulic ports; wherein the control slide comprises a first controlsegment which is delimited in the axial direction by a first controledge; wherein the slide housing comprises a first housing segment thatcooperates with the first control segment to control a first flow crosssection for hydraulic flow within the inner diameter of the slidehousing at the first control segment; wherein the first control edge ofthe first control segment in cooperation with the first housing segmentis configured to modify size of the first flow cross section at thefirst control segment based on rotational position of the control slidewithin the slide housing; wherein the control slide further comprises asecond control segment which is delimited in the axial direction by asecond control edge: wherein the slide housing comprises a secondhousing segment that cooperates with the second control segment tocontrol a second flow cross section for hydraulic flow within the innerdiameter of the slide housing at the second control segment; wherein thesecond control edge of the second control segment in cooperation withthe second housing segment is configured such that for a fixed axialposition of the control slide within the slide housing, the second flowcross section at the second control segment is constant in size for anyrotational position of the control slide within the slide housing;wherein the second control segment of the control slide comprises aregulating control segment in an outflow region of the slide housingwhich connects the slide housing to the input port.